Method and means for perforating well casings



y 21, 1940- H. M. GREENE 2,201,290

METHOD AND MEANS FOR PERFORATING WELL CASINGS' Filed March 4, 1939 2 Sheets-Sheet 1 /z r 76 l7 l3 I 20 g z/ l g 7 A TTORNEY 11v VENTOR.

y 1940. I H. M. GREENE 2,201,290

By W ATTORNEY Patented May 21, 1940- UNITED STATES METHOD AND MEANS FOR PERFORATING WELL CASINGS Haskell M. Greene, Whittier, Calif. Application March 4, 1939, Serial No. 259,828

. 5 Claims.

This invention relates to a method of and means for perforating a well casing in position in a well hole.

The present method of perforating a well casing in position in a well hole by means of the conventional gun perforator has several objectional features. For example, burrs are left on the inside of the casing around the perforations by the conventional gun perforator, which burrs damage a swab or similar tool, unless they are removed by means of a rasp or other tool. Sometimes the casing is split or otherwise damaged by the bullet fired from the gun perforator.

An object of my invention is to provide a method of perforating a well casing in which the edges of the perforations on the inside of the casing will be smooth.

Another object of my invention is to provide a casing having explosive charges attached thereto.

Another object of my invention is to provide a casing having a plurality of chambers containing explosive charges.

Another object of my invention is to provide a method of perforating a well casing in place in a well hole which consists in providing chambers in the wall of said casing, placing explosive charges in said chambers, providing closure means for said chambers, lowering said easing into position in the well hole, and selectively firing as many of said explosive charges as desired, thereby perforating said casing and shattering the material adjacent to said casing.

My invention has many other objects, advantages, and features, some of which, with the foregoing, will be set forth at length in the following description where I shall outline certain forms of the invention, which I have selected for illustration in the drawings accompanying and forming a part of the present specification. In

the said drawings, I have shown certain forms of my invention, but it is to be understood that I do not limit myself to such forms, since the invention, as expressed in the claims, may be embodied in a large plurality of forms.

Figure 1 is a side elevation, partly broken away, of a section of casing in a well hole with the means for exploding the explosive charges in place.

Figure 2 is an enlarged longitudinal section of the casing and adjacent structure, after several of the explosive charges have been exploded.

Figure 3 is an enlarged transverse section of a part of the casing showing one of the chambers.

Figure 4 is the same as Figure 3, after the explosive charge in the chamber has been exploded.

Figure 5 is an enlarged transverse section of a part of the casing showing another form of chamber.

Figure 6 is the same as Figure 5, after the explosive charge has been exploded.

Figure 1 illustrates a well casing I0 provided with a plurality of chambers containing explosive charges. As shown in Figure 3, holes H are made in the casing. Plugs 12 are thenforced into the holes II. The plugs l2 are preferably made of a good grade of hard steel and welded in place as indicated by the numeral; l3, ,so,.;that the casing Ill instead of being weakened at'the point where the perforation is made;- is in fact strengthened. The inner wall of the plugmay be comparatively thin, and the outer-portion of i the plug may be threaded as indicated by the numerals I 4 and I5 respectively.

The plugs I2 are provided with openings l6 which are of the same diameter as the desired perforations, and which form chambers into which explosive charges are placed. The explosive charge may be a gelatinized nitro cellulose, of the type commonly used as a base for rifle and pistol powders. The chambers are then closed, for example, by means of threaded (caps H, the outer walls I8 of which are preferably somewhat smaller in thickness than the inner walls M of the plugs.

The casing I0 is provided with as many rows of explosive charges as desired which are spaced apart as desired, and with either two, four, six or any other desired number of explosive charges in each row.

The casing is run into position in the well hole, and may or may not be cemented in the formation, depending upon whether or not it is necessary to shut off formations containing water.

Any convenient means may be used to selectively fire as many of said explosive charges as desired, for example, electrical heating elements, or low grade explosives. In the drawings I have illustrated an electrical heating means to fire the explosivecharges, although chemical heating means somewhat similar to that described in U. S. Patent No, 2,144,208, issued Jan. 17, 1939, may be conveniently used.

A container 20 having an electrical heating element 2| is lowered in the well hole by means well hole.

explosive charge in the casing. After the container 20 has been lowered to the position where the perforations are desired, current is passed through the heating element 2| by means of the insulated electric cables 22 and 23, which causes the heating element to give of! sumcient heat to explode the explosive charge in the chambers adjacent thereto, thereby forcing the wall it in and the cap I! out. The cap l1 acts as a bullet in shattering the formation as shown in Figure 2. As shown in Figure 4 the walls of the perforations on the inside of the casing iii are smooth.

Due to the fact that the wall l8 of the cap i'l is somewhat smaller in thickness than the wall it of the plug it, most of the charge is exploded outside of the walls of the casing. The container 20 is preferably made of such length that only one row of explosive charges will be fired at a time, although the containermay be made of such length that 2 or more rows of explosive charges. will be fired every time that current is passed through the heating element.

The container 20 is then raised or lowered to the position where it is desired to make another row of perforations, and the current is again passed through the heating element 2| in order to explode the explosive charges adjacent thereto. The above operations are repeated until the casing is perforated as desired.

Instead of using the above means to fire the explosive charges, a container provided with a battery, timeswitch, and heating element may be used to fire the explosive charges. By means of such a container, it is not necessary to use a special insulated electric cable, and the conventional sand line or drilling cable can be used to lower the container into position. The time switch is set to operate a short time in advance in order to allow for the time necessary to lower the container into the desired position in the As the time switch operates, current from the battery causes the heating element to generate suflicient heat to explode the charges I in the explosive chambers adjacent thereto. A

similar means can readily be used to ignite Thermit' when that compound is used to create heat in order to explode the charges. I

In the modification shown in Figure 5, the easing is provided with enlarged portions 40 and threaded openings 4! are made in said enlarged portions, which openings do not extend through to the interior of, the casing. Threaded plugs 42 provided with chambers 43 which are of the same diameter as that of the desired perforations are threaded into the threaded openings ll after the chambers 43 are filled with explosive charges.

The'portion of plug indicated by the numeral 44 adjacent the head portion 46 may be recessed in order to make certain of the position where the plug will fracture when the charge is exploded. In exploding a charge in a plug of this type, the head portion 4! acts as a bullet in shattering the surrounding formation.

From the foregoing description taken in con nection with the accomanying drawings, the uses, advantages, and operation of my invention will be readily understood by those skilled in the art to which the invention appertains. I While I have described the principle of operation together with the forms of my invention which I now consider to be the best embodiment thereof, I desire to have it understood that the articles shown are merely illustrative and that the invention is not to be limited to the detailsdisclosed herein, but is to be accorded the full scope of the appended claims.

I claim:

1. A well-casing having an explosive charge attached thereto which charge is adapted to be fired while attached to said well-casing.

2. A well-casing having an explosive charge in the walls of said well-casing. I V

3. A well-casing provided with a plurality of chambers containing explosive material.

4. A well-casing having an explosive charge in the walls of said well-casing, said explosive charge being adapted to be tired after said wellcasing is in position in a well-hole.

5. A well-casing provided with a. plurality of chambers containing explosive material, said explosive material being adapted to be fired after the well -casing is in position in a well-hole.

\ M. GREENE. 

